1. Field of the Invention
The present invention relates to a cassette type recording unit. More particularly, it relates to a cassette type recording unit containing a solid-state memory, an electro-magnetic transducing element, a magnetism detecting element to detect magnetism in an erasing head and a switching circuit for switching the operations of recording and reproducing, whereby recording and reproducing can be automatically performed with use of an ordinally magnetic tape cassette type magnetic tape recording apparatus.
2. Discussion of Background
FIG. 3 is a plane view partly cross-sectioned of a magnetic tape cassette which has been widely used, wherein a reference numeral 1 designates a casing, numerals 2 designate a pair of hubs 10 disposed in the casing 1, numerals 3 designates the openings of the hubs 2 and a numeral 4 designates a magnetic tape. A window 6 for pinch roller a window 7 for recording/reproducing head, an aperture 8 for capstan and a window 9 for erasing head are respectively formed in the front face of the magnetic tape cassette, the front face constituting an area for permitting the transport of the magnetic tape 4. Further, guide pins 10 and a guide roller 11 are also formed in the casing 1 to thereby give stable running or transport of the magnetic tape 4. When the magnetic tape cassette is mounted on a tape cassette type magnetic tape recording apparatus to conduct recording or reproducing, guide posts formed in the recording apparatus are inserted in reference holes 5 formed at both sides of the magnetic tape cassette, and pawls formed on the hub driving shafts of the recording apparatus are meshed with six pins formed in the openings 3 of the hubs, whereby a rotational force is applied to the hubs 2. Further, a capstan shaft of the recording apparatus is fitted to the aperture 8 of capstan, and a pinch roller pushes the magnetic tape 4 to the capstan through the window 6 for pinch roller. The rotation of the hubs 2 moves the magnetic tape 4 under the condition that the magnetic tape 4 is held by the pinch roller and the capstan. When the magnetic tape runs in contact with the recording/reproducing head RW of the recording apparatus, which enters in the window 7 for the recording/reproducing head, a magnetization pattern is formed in the magnetic tape 4 due to a change of magnetism in response to a signal current to the magnetic head, whereby the recording is magnetically performed in the magnetic tape 4.
Prior to the recording of the magnetic tape 4 by the recording/reproducing head RW, data recorded on the magnetic tape 4 are erased by means of an erasing head IH of the recording apparatus. As the erasing head IH, there have been known two kinds of erasing head: one formed by a permanent magnet which is in contact with the magnetic tape 4 in recording operations and is separated from the magnetic tape 4 in reproducing operations, and the other which is normally in contact with the magnetic tape, wherein it is excited by supplying an erasing current in recording operations and is deenergized by interrupting the erasing current in reproducing operations.
In the reproducing operations, the magnetic tape on which data are recorded is caused to run while it is brought into contact with the recording/reproducing head RW. Then, an electromotive force is produced in the coil of the recording/reproducing head RW in response to changes in a magnetic flux generated from the magnetic tape. Thus, an output for reproducing the data is obtainable.
In the conventional magnetic tape cassette having the magnetic tape 4 as a recording medium, the breaking or the twisting of the magnetic tape 4 or jamming of the tape 4 due to irregularity of during winding may take place. It results in the construction of the magnetic tape cassette having the magnetic tape 4. In the case of bad conditions during stocking the magnetic tape, curling or elongation is caused in the magnetic tape, or the quality of recorded data changes by the influence of magnetism.